Trimming mechanism for sewing machines



J. R. MOFFATT. TRIMMING MECHANISM FOR SEWING MACHINES.

APPLICATION FILED MAR 2 I918.

Patented Jan. 17, 1922.

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J. R. MOFFATT. TRIMMING MECHANISM FOR SEWING MACHINES.

APPLICATION FILED MAN- 2, I918.

Patented Jan. 17,1922.

3 SHEETS-SHEET 2.

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TRIMMING MECHANISM FOR SEWING MACHINES.

APPLICATION FILED mung. 1918. v

Patented Jan. 17, 1922.

3 SHEETS-SHEET 3.

JAMES R. MOFFATT, OF CHICAGO, ILLINOIS, ASSIGNOR TO UNIO N SPECIAL MACHINE COMPANY, 01; CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TRIMMING MECHANISM FOR SEWING MACHINES.

Specification of Letters Patent.

Patented Jan. 17, 1922.

Application filed March 2, 1918. Serial No. 220,047.

To all whom it may concern:

Be it known that I, JAMEs R. MorrA'r'r, a citizen of the United States, residing at Chicago, in the county of Cook, State of Illinois, have invented certain new and useful Improvements in Trimming Mechanism for Sewing Machines, of which the following is a description, reference being had to the accompanying drawing and to the ures of reference marked thereon.

The invention relates to new and useful improvements in trimming mechanism for sewing machines and more particularly to a trimming mechanism wherein the blades are horizontally disposed and are adapted to trim the upturned edges of two fabric sec tions which are subsequently oined to form a fiat seam.

An object of the invention is to provide a trimming mechanism of the above character wherein the movable trimming blade is mounted to oscillate about the guide bar associated with the presser bar carrying the presser foot, as an axis, and wherein the supporting device for the movable trimming: blade is oscillated by a link connection with the needle lever of the machine.

A further object of the invention is to provide a trimming mechanism having a horizontally disposed trimming blade, with means for supporting the blade so that said blade may be shifted laterally for bringing the same into proper cooperative relation with the fixed trimming blade.

A still further object of the invention is to provide means for clamping the horizontally moving blade to its supporting arm so that said blade may be firmly supported and held from springing laterally it 00- operates with the stationary blade.

These and other objects will in part be obvious and will in part be hereinafter more fully disclosed.

In the drawings, which show by way of illustration, one embodiment of the invention:-

Figure 1 is a front view of a machine having my improvements applied thereto;

Figure 2 is an end view of the same;

Fig. 3 is a view partly in plan and partly in section showing the trimming blades and the operating mechanism therefor and also showing the presser foot in plan, the cross thread laying devices co-operating with the needles and the combined cover plate and deflector which houses the cross thread la lng devices and deflects the trimmed 6a strip away from the same, the deflector belng shown in retracted position;

F 1g. 4 1s a perspective view of the presser foot, the trimming blades, the mechanism for operating the movable blade, a portion of the needles, the thread hook and the thread deflecting finger;

Fig. 5 is a detail from the rear of the machine showing the manner of mounting the lever for operating the movable trimmmg blade;

Fig. 6 is a detail showing in plan the manner in which the combined cover plateand deflector houses the thread hook and needlesand deflects the trimmed off strip.

My improved trimming mechanism is shown as applied to a flat bed machine having a plurality of needles with cross thread laying devices for laying a cross thread which is stitched down by the needle threads. This cross thread laying mechanism includes a movable thread hook. In advance of the needles are located the trimming blades which are horizontally disposed for trimming the upturned edges of fabric sections. The movable blade is carried by a lever which is fulcrumed on the guide bar associated with the presser for carrying the presser foot, said lever is held from sidewise movement on the guide bar and is oscillated by a link connection with the needle lever. The movable blade is connected to a supporting head which is vertically adjustable on the lever. (lo-operating with the trimming blades is a combined cover plate and deflector which is secured to the machine at a point in rear of the thread hook and extends around so as to coverthe needles and thread hook and disposed relative to the needles and the trimming blade so as to deflect the trimmed ofi strip.

Referring more in detail to the drawings. I have shown my invention as applled to a sewing machine having a work support 1,.

a standard 2 and an overhanging arm 3. Mounted to reciprocate in the overhanging arm is a needle bar 4 carrying, as herein shown, three need es 5, 6 and 7 The needle bar is reciprocated by a needle lever 8 which is fulcrumed at 9 on the standard 2. This needle lever is oscillated by a link 10 which co-operates with an eccentric on the main shaft of the machine.

The presser foot is indicated at 11 in the drawings, and said presser foot is carried by a presser bar 12, mounted in the overhanging arm. Associated with the presser bar 12 is a guide bar 13. The guide bar 13 is secured to the presser bar by a clamp 1 1. The presser foot is provided with a guide slot 15 which extends from the front end thereof rearwardly in the line of feed and terminates just in advance of the opening 16, for the needles. The fabric sections to be united have their edges upturned and these upturned edges pass through the guide slot 15. A fixed trimming blade 17 is clamped to the presser foot by means of a clamping plate 18. The presser foot is re cessed to receive this fixed blade. Co-operat'- ing with the fixed blade 17 is a movable trimming blade 19 having a guiding finger 20 overlapping the stationary blade and a cutting edge 21 which co-operates with the .Nhen it is desired to cover the meeting or overlapped edges of the fabric sections a cross thread is used and this cross thread is laid in loop form by a hook 22 which cooperates with athread finger 23 and a cross thread guiding eye 24:. This particular cross thread laying mechanism per se forms no part of the present invention but is shown, described and claimed in my co-pending application, Serial No. 220,0t6 filed of even date herewith.

The thread hook 22 is oscillated by a lever 25, which in turn is connected to a link 26 and the link 26 is connected to an arm 27 on the cross shaft 28. The cross shaft 28 carries an arm 29 which is connected to an eccentric rod 30 co-operating with an'eccentric on the main shaft.

The movable trimming blade 19 is supported and oscillated by a lever 31. The lever 31 is fulcrumed so as to turn about the axis of the guide bar Said lever is in the form of a sleeve 32 which surrounds the guide bar. Extending forwardly from said sleeve is an arm 33. At the for- .ward end of said arm is mounted a supporting head 34; which carries the trimming blade 19. The end of the arm is formed with a recess adapted to receive arib 35 on 1 ,eoasov said head 3 1. A screw 36 adjustably'secures the head in place and permits limited vertical adjustment of the head. 7 Said head is formed with a downwardly projecting split supporting arm 37. The blade is disposed between the split sections of the arm 37 and is clamped therein by a screw 38 which threads into the split sections of the arm and these split sections may be drawn together by the screw. Forwardly projecting fingers 39 engage the upper face of the blade and prevent thesame from springing upwardly. The sleeve 32 also carries a forwardly projecting arm a0 which. is provided with a ball stud 41 and a link 42 engages this ball stud 41. 7 The link 42 at its opposite end engages a ball stud 43 carried by the needle leverat a point below the fulcruin9. As the needle lever oscillates the link 12 will move endw'ise and this will oscillate the lever 31 carrying the movable trimming blade. The lever 31 is provided with an arm 44 which is spaced from the A sleeve 32 and engages the guide bar 13. A collar 15 is secured to the guide bar between this arm and the sleeve and prevents the lever from moving endwise of the guide bar 13. 7

.From the above it will be apparent as the needle lever is oscillated the lever 31 will also be oscillated and movethe trimming blade 19 back and forth across the slot 15. Said blade may be adjusted vertically to bring it into proper co-operative relation with the fixed blade 17 and when properly positioned it will be the lever 31. V

Pivoted at 46 to the shank portion of the presser foot and in rear of the 'presser bar 12 is a combined guard and deflector 47. This guard is shaped so as to extend about the thread hook, completely housing the thread hook, the thread finger and the needles. Said guard and deflector extends across the movable blade and is positioned relative thereto so as to engage the trimmed 0d portions of the fabric sections and deflect the same away from the thread hook and the needles.

It is obvious that minor changes in the details of construction and the arrangement of the parts may be made without departing from the spirit of the invention as set forth in the appended claims.

Having thus described my invention what rigidlyheld in place on 7 I claim as new and desire to secure by Letters Patent is V V 1. The combination of a presser foot, 2. presser bar, a guide bar attached to the presser bar, a lever pivotally;'supporte d by plane, means for preventing thelever from moving endwise of the guide bar, a fixed trimming blade carried by the presser foot, a movable trimming blade carried by said 7 v the guide bar so asto swing in a horizontal lever and adapted to co-operate with the fixed trimming blade, said presser foot having a guiding slot for directing the upturned edges of fabric sections to the trimming blade.

2. The combination of a presser foot, a presser bar carrying the presser foot, a guide bar attached to the presser bar, a lever mounted to move horizontally on said guide bar, an arm attached to the lever and engaging the guide bar, a collar fixed to the guide bar between the arm and the lever for preventing the lever from moving endwise of the guide bar, means for oscillating the lever, a trimming blade carried by the lever and moving horizontally across the presser foot, a trimming blade co-operating with the movable blade, said presser foot having a guiding slot for directing upturned edges of fabric sections to the trimming blade.

3. The combination of a presser foot, horizontally disposed trimming blades, a lever for supporting and oscillating one of said blades, a head attached to said lever and supporting one or" said blades, means whereby said head may be vertically adjusted on said lever, said head having a split arm and a clamping screw for causing said split arm to engage and clamp the movable trimming blade, said arm having forwardly projecting fingers overlying the movable trimming blade for preventing the same from being deflected.

In testimony whereof, I afiix my signature, in the presence of two witnesses.

JAMES R. MOFFATT.

Witnesses S. GEORGE TATE, RALPH S. KELSO. 

